Saving PDF Files with Swift in iOS and display them

I'm new at developing apps for iOS with Swift and I do understand the basics about building an app.Excuse me in advance if my questions are a bit stupid but I couldn't find answers I could have worked with...

However, I want to build an app which also includes the possibility to show and save PDFs local inside the app and display them ( as a FileSystem) within a tableview and open them when I tap on one PDF.

Here are my important questions for that:

1. How do I save a PDF local on my app ( for example if the user can enter a url) and where exactly will it save it ?

2. When saved, how can I show all the local storaged files within a tableview to open them?

As I am new as a developer with Xcode and Swift, is there another tip you can give me to find out how to find tips easier within the doc/internet ?